Traditionally, quality control in the pharmaceutical industry has related to the type, purity, and amount of tablet ingredients. However, quality also relates to defects which can be detected by visual inspection such as dirt, surface blemishes, and surface chips. Although many visual inspections can be performed by operators, manual inspection can be slow, expensive and subject to operator error. Thus, automated vision systems for quality control in the pharmaceutical industry are extremely important.
One such vision system automatically inspects the surface of pharmaceutical tablets and separates the tablets based on predetermined parameters. The system uses a plurality of charge couple device (CCD) high resolution line (one dimensional) sensor cameras to inspect the surfaces of a tablet. In this system tablets stored in a hopper are fed by a vibratory feeder to a flow-control turntable, where they are aligned and proceed to a suction belt system. The suction belt system carries the tablets past a series of line sensor CCD cameras which sequentially inspect the perimeter, the top, and the bottom of each individual tablet. The images are converted into video electronic signals. The signals are differentiated in order to obtain a pattern. The pattern is then compared with the corresponding number of differentiated peaks from a satisfactory tablet, and the defective tablets are identified. Defective tablets are rejected by a pneumatic selector and satisfactory tablets are retained. This particular system is manufactured by Kanebo Engineering (Osaka, Japan).
One recent type of drug delivery device (tablet) contains the active ingredient surrounded by a semipermeable membrane. The semipermeable membrane is permeable to water but impermeable to the active ingredient. The device also includes a substance that swells upon the absorption of water. A coating surrounds the device and a small hole is provided through both the coating and semipermeable membrane, providing a release path for the active ingredient. In use, water passes through the semipermeable membrane, swells the absorptive substance pushing the active ingredient through the hole into the use environment. Since the presence of the hole is important to the intended functioning of the device, verification of the hole presence is equally important. One verification procedure utilizes a beam splitter which checks the discharge intensity of the laser beam used to drill the hole. This is an indirect procedure that merely verifies that the laser was discharged.
Although the above systems provide solutions for automating the inspection of pharmaceutical tablets, there is continual search in this field of art for alternative automated vision inspection systems.